The long-term objective of this project is aimed at elucidating the dynamic host-virus interactions, specifically focusing on integrase (IN) and INI1/hSNF5, and to utilize this knowledge for the design of drugs for anti-AIDS therapy. INI1 is a core component of the chromatin remodeling SWI/SNF complex and a tumor suppressor. INI1/hSNF5 is specifically incorporated into the HIV-1 virions and a truncation mutant of INI1/hSNF5 dominant negatively inhibits HIV-1 replication. INI1/hSNF5 harbors a masked nuclear export signal that mediates the hCRM1/exportinl dependent nuclear export. We have found that INI1/hSNF5 is also present in another novel complex, distinct from the SWI/SNF complex, the component of which is incorporated into HIV-1 virions. We hypothesize that during assembly and particle production, INI1/hSNF5, along with its novel nuclear complex, is signaled to get exported to the cytoplasm, docks itself onto IN portion of Gag-Pol, and gets assembled into the HIV-1 virions. In the target cells, INI1 complex may facilitate the integration and/or regulate transcription of the provirus. In this proposal, in the specific aim I, using RNA interference and transdominant mutants we will determine if INI 1 and SAP 18 are required for early and late events of HIV-1 replication in producer cells or target cells. In the specific aim II, we will characterize INI1-assocated proteins (such as SAP18) and mechanism of their incorporation into HIV-1 virions. We will purify the novel INI1-SAP18 multi-protein complex and determine the dependence on IN. In the specific aim III, we will carry out biochemical and genetic analysis to determine the functional significance of INI1 and its associated proteins such as SAP18 to HIV-1 replication. We will test the effect of purified INI 1 and complexes on in vitro integration, isolate and characterize interaction defective mutants of IN, INI 1 and SAP 18 and their intra-molecular and inter-molecular, allele specific and non-allele specific revertants. In the specific aim IV, we will determine if nuclear export property of INI1/hSNF5 is important for incorporation into HIV-1 virions and for transdominant inhibition of early and late events. Our proposal will provide a comprehensive account of mechanism and significance of recruitment of INI1-associated multi-protein complex to HIV-1 and elucidate the higher order structure/function relationship of IN with its host proteins. Understanding the vitality of host-virus interactions is likely to provide novel targets and insights for designing effective antivirals against HIV-1.